Mountain formation

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Thrust and reverse fault movement are an important component of mountain formation. Mountain by reverse fault.gif
Thrust and reverse fault movement are an important component of mountain formation.
Illustration of mountains that developed on a fold that thrusted. Lewis overthrust fault nh10f.jpg
Illustration of mountains that developed on a fold that thrusted.

Mountain formation occurs due to a variety of geological processes associated with large-scale movements of the Earth's crust (tectonic plates). [1] Folding, faulting, volcanic activity, igneous intrusion and metamorphism can all be parts of the orogenic process of mountain building. [2] The formation of mountains is not necessarily related to the geological structures found on it. [3]

Contents

From the late 18th century until its replacement by plate tectonics in the 1960s, geosyncline theory was used to explain much mountain-building. [4] The understanding of specific landscape features in terms of the underlying tectonic processes is called tectonic geomorphology , and the study of geologically young or ongoing processes is called neotectonics . [5] [ clarification needed ]

Types of mountains

There are five main types of mountains: volcanic, fold, plateau, fault-block, and dome. A more detailed classification useful on a local scale predates plate tectonics and adds to these categories. [6]

Volcanic mountains

Annotated view includes Ushkovsky, Tolbachik, Bezymianny, Zimina, and Udina stratovolcanoes of Kamchatka, Russia. Oblique view taken on November 12, 2013, from ISS. ISS-38 Kliuchevskoi Volcano on Kamchatka.jpg
Annotated view includes Ushkovsky, Tolbachik, Bezymianny, Zimina, and Udina stratovolcanoes of Kamchatka, Russia. Oblique view taken on November 12, 2013, from ISS.
Stratovolcanoes associated with a subduction zone (left) and a spreading ridge volcano (right). A hotspot volcano is center. Volcanoes at subduction.JPG
Stratovolcanoes associated with a subduction zone (left) and a spreading ridge volcano (right). A hotspot volcano is center.

Movements of tectonic plates create volcanoes along the plate boundaries, which erupt and form mountains. A volcanic arc system is a series of volcanoes that form near a subduction zone where the crust of a sinking oceanic plate melts and drags water down with the subducting crust. [9]

The Dome of Vitosha mountain next to Sofia Sofia-vitosha-kempinski.jpg
The Dome of Vitosha mountain next to Sofia

Most volcanoes occur in a band encircling the Pacific Ocean (the Pacific Ring of Fire), and in another that extends from the Mediterranean across Asia to join the Pacific band in the Indonesian Archipelago. The most important types of volcanic mountain are composite cones or stratovolcanoes and shield volcanoes . [10] [11]

A shield volcano has a gently sloping cone because of the low viscosity of the emitted material, primarily basalt. Mauna Loa is the classic example, with a slope of 4°-6°. (The relation between slope and viscosity falls under the topic of angle of repose. [12] ) A composite volcano or stratovolcano has a more steeply rising cone (33°-40°), [13] because of the higher viscosity of the emitted material, and eruptions are more violent and less frequent than for shield volcanoes. Examples include Vesuvius, Kilimanjaro, Mount Fuji, Mount Shasta, Mount Hood and Mount Rainier. [14]

Fold mountains

Zard-Kuh, a fold mountain in the central Zagros range of Iran. Kolunchin Zardkuh.JPG
Zard-Kuh, a fold mountain in the central Zagros range of Iran.

When plates collide or undergo subduction (that is, ride one over another), the plates tend to buckle and fold, forming mountains. While volcanic arcs form at oceanic-continental plate boundaries, folding occurs at continental-continental plate boundaries. Most of the major continental mountain ranges are associated with thrusting and folding or orogenesis. Examples are the Balkan Mountains, the Jura and the Zagros mountains. [15]

Block mountains

Fault-block mountain of the tilted type. Fault block mountain.JPG
Fault-block mountain of the tilted type.
Sierra Nevada Mountains (formed by delamination) as seen from the International Space Station. Sierra Nevada Mountains.JPG
Sierra Nevada Mountains (formed by delamination) as seen from the International Space Station.

When a fault block is raised or tilted, a block mountain can result. [17] Higher blocks are called horsts, and troughs are called grabens . A spreading apart of the surface causes tensional forces. When the tensional forces are strong enough to cause a plate to split apart, it does so such that a center block drops down relative to its flanking blocks.

An example is the Sierra Nevada range, where delamination created a block 650 km long and 80 km wide that consists of many individual portions tipped gently west, with east facing slips rising abruptly to produce the highest mountain front in the continental United States. [18] [19]

Another example is the Rila–Rhodope massif in Bulgaria, including the well defined horsts of Belasitsa (linear horst), Rila mountain (vaulted domed shaped horst) and Pirin mountain—a horst forming a massive anticline situated between the complex graben valleys of the Struma and Mesta rivers. [20] [21] [22]

Uplifted passive margins

Unlike orogenic mountains there is no widely accepted geophysical model that explains elevated passive continental margins such as the Scandinavian Mountains, eastern Greenland, the Brazilian Highlands, or Australia's Great Dividing Range. [23] [24] Different elevated passive continental margins most likely share the same mechanism of uplift. This mechanism is possibly related to far-field stresses in Earth's lithosphere. According to this view elevated passive margins can be likened to giant anticlinal lithospheric folds, where folding is caused by horizontal compression acting on a thin to thick crust transition zone (as are all passive margins). [25] [26]

Models

Hotspot volcanoes

Hotspots are supplied by a magma source in the Earth's mantle called a mantle plume. Although originally attributed to a melting of subducted oceanic crust, recent evidence belies this connection. [27] The mechanism for plume formation remains a research topic.

Fault blocks

Several movements of the Earth's crust that lead to mountains are associated with faults. These movements actually are amenable to analysis that can predict, for example, the height of a raised block and the width of an intervening rift between blocks using the rheology of the layers and the forces of isostasy. Early bent plate models predicting fractures and fault movements have evolved into today's kinematic and flexural models. [28] [29]

See also

Related Research Articles

<span class="mw-page-title-main">Plate tectonics</span> Movement of Earths lithosphere

Plate tectonics is the scientific theory that Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of continental drift, an idea developed during the first decades of the 20th century. Plate tectonics came to be accepted by geoscientists after seafloor spreading was validated in the mid-to-late 1960s. The processes that result in plates and shape Earth's crust are called tectonics. Tectonic plates also occur in other planets and moons.

<span class="mw-page-title-main">Supercontinent</span> Landmass comprising more than one continental core, or craton

In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", which leaves room for interpretation and is easier to apply to Precambrian times. To separate supercontinents from other groupings, a limit has been proposed in which a continent must include at least about 75% of the continental crust then in existence in order to qualify as a supercontinent.

<span class="mw-page-title-main">Orogeny</span> The formation of mountain ranges

Orogeny is a mountain-building process that takes place at a convergent plate margin when plate motion compresses the margin. An orogenic belt or orogen develops as the compressed plate crumples and is uplifted to form one or more mountain ranges. This involves a series of geological processes collectively called orogenesis. These include both structural deformation of existing continental crust and the creation of new continental crust through volcanism. Magma rising in the orogen carries less dense material upwards while leaving more dense material behind, resulting in compositional differentiation of Earth's lithosphere. A synorogenic process or event is one that occurs during an orogeny.

<span class="mw-page-title-main">Subduction</span> A geological process at convergent tectonic plate boundaries where one plate moves under the other

Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second plate, the heavier plate dives beneath the other and sinks into the mantle. A region where this process occurs is known as a subduction zone, and its surface expression is known as an arc-trench complex. The process of subduction has created most of the Earth's continental crust. Rates of subduction are typically measured in centimeters per year, with rates of convergence as high as 11 cm/year.

Obduction is a geological process whereby denser oceanic crust is scraped off a descending ocean plate at a convergent plate boundary and thrust on top of an adjacent plate. When oceanic and continental plates converge, normally the denser oceanic crust sinks under the continental crust in the process of subduction. Obduction, which is less common, normally occurs in plate collisions at orogenic belts or back-arc basins.

<span class="mw-page-title-main">Tectonics</span> Process of evolution of the Earths crust

Tectonics are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of planetary tectonics extends the concept to other planets and moons.

<span class="mw-page-title-main">Rift</span> Geological linear zone where the lithosphere is being pulled apart

In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-graben with normal faulting and rift-flank uplifts mainly on one side. Where rifts remain above sea level they form a rift valley, which may be filled by water forming a rift lake. The axis of the rift area may contain volcanic rocks, and active volcanism is a part of many, but not all, active rift systems.

<span class="mw-page-title-main">Geology of the United States</span>

The richly textured landscape of the United States is a product of the dueling forces of plate tectonics, weathering and erosion. Over the 4.5 billion-year history of the Earth, tectonic upheavals and colliding plates have raised great mountain ranges while the forces of erosion and weathering worked to tear them down. Even after many millions of years, records of Earth's great upheavals remain imprinted as textural variations and surface patterns that define distinctive landscapes or provinces.

<span class="mw-page-title-main">Orogenic belt</span> Zone affected by mountain formation

An orogenic belt, orogen, or mobile belt, is a zone of Earth's crust affected by orogeny. An orogenic belt develops when a continental plate crumples and is uplifted to form one or more mountain ranges; this involves a series of geological processes collectively called orogenesis.

<span class="mw-page-title-main">Rock cycle</span> Transitional concept of geologic time

The rock cycle is a basic concept in geology that describes transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous. Each rock type is altered when it is forced out of its equilibrium conditions. For example, an igneous rock such as basalt may break down and dissolve when exposed to the atmosphere, or melt as it is subducted under a continent. Due to the driving forces of the rock cycle, plate tectonics and the water cycle, rocks do not remain in equilibrium and change as they encounter new environments. The rock cycle explains how the three rock types are related to each other, and how processes change from one type to another over time. This cyclical aspect makes rock change a geologic cycle and, on planets containing life, a biogeochemical cycle.

<span class="mw-page-title-main">Geology of Australia</span>

The geology of Australia includes virtually all known rock types, spanning a geological time period of over 3.8 billion years, including some of the oldest rocks on earth. Australia is a continent situated on the Indo-Australian Plate.

<span class="mw-page-title-main">Passive margin</span> Transition between oceanic and continental lithosphere that is not an active plate margin

A passive margin is the transition between oceanic and continental lithosphere that is not an active plate margin. A passive margin forms by sedimentation above an ancient rift, now marked by transitional lithosphere. Continental rifting forms new ocean basins. Eventually the continental rift forms a mid-ocean ridge and the locus of extension moves away from the continent-ocean boundary. The transition between the continental and oceanic lithosphere that was originally formed by rifting is known as a passive margin.

<span class="mw-page-title-main">Volcanic belt</span> Large volcanically active region

A volcanic belt is a large volcanically active region. Other terms are used for smaller areas of activity, such as volcanic fields or volcanic systems. Volcanic belts are found above zones of unusually high temperature where magma is created by partial melting of solid material in the Earth's crust and upper mantle. These areas usually form along tectonic plate boundaries at depths of 10 to 50 kilometres. For example, volcanoes in Mexico and western North America are mostly in volcanic belts, such as the Trans-Mexican Volcanic Belt that extends 900 kilometres (560 mi) from west to east across central-southern Mexico and the Northern Cordilleran Volcanic Province in western Canada. In the case of Iceland, the geologist G.G. Bárdarson in 1929 identified clusters of volcanic belts while studying the Reykjanes Peninsula.

In geology, epeirogenic movement is upheavals or depressions of land exhibiting long wavelengths and little folding apart from broad undulations. The broad central parts of continents are called cratons, and are subject to epeirogeny. The movement may be one of subsidence toward, or of uplift from, the center of Earth. The movement is caused by a set of forces acting along an Earth radius, such as those contributing to isostasy and faulting in the lithosphere.

Non-volcanic passive margins (NVPM) constitute one end member of the transitional crustal types that lie beneath passive continental margins; the other end member being volcanic passive margins (VPM). Transitional crust welds continental crust to oceanic crust along the lines of continental break-up. Both VPM and NVPM form during rifting, when a continent rifts to form a new ocean basin. NVPM are different from VPM because of a lack of volcanism. Instead of intrusive magmatic structures, the transitional crust is composed of stretched continental crust and exhumed upper mantle. NVPM are typically submerged and buried beneath thick sediments, so they must be studied using geophysical techniques or drilling. NVPM have diagnostic seismic, gravity, and magnetic characteristics that can be used to distinguish them from VPM and for demarcating the transition between continental and oceanic crust.

This is a list of articles related to plate tectonics and tectonic plates.

<span class="mw-page-title-main">Geology of Russia</span>

The geology of Russia, the world's largest country, which extends over much of northern Eurasia, consists of several stable cratons and sedimentary platforms bounded by orogenic (mountain) belts.

Tectonic subsidence is the sinking of the Earth's crust on a large scale, relative to crustal-scale features or the geoid. The movement of crustal plates and accommodation spaces produced by faulting brought about subsidence on a large scale in a variety of environments, including passive margins, aulacogens, fore-arc basins, foreland basins, intercontinental basins and pull-apart basins. Three mechanisms are common in the tectonic environments in which subsidence occurs: extension, cooling and loading.

Ultra-high-pressure metamorphism refers to metamorphic processes at pressures high enough to stabilize coesite, the high-pressure polymorph of SiO2. It is important because the processes that form and exhume ultra-high-pressure (UHP) metamorphic rocks may strongly affect plate tectonics, the composition and evolution of Earth's crust. The discovery of UHP metamorphic rocks in 1984 revolutionized our understanding of plate tectonics. Prior to 1984 there was little suspicion that continental rocks could reach such high pressures.

The geology of Sicily records the collision of the Eurasian and the African plates during westward-dipping subduction of the African slab since late Oligocene. Major tectonic units are the Hyblean foreland, the Gela foredeep, the Apenninic-Maghrebian orogen, and the Calabrian Arc. The orogen represents a fold-thrust belt that folds Mesozoic carbonates, while a major volcanic unit is found in an eastern portion of the island. The collision of Africa and Eurasia is a retreating subduction system, such that the descending Africa is falling away from Eurasia, and Eurasia extends and fills the space as the African plate falls into the mantle, resulting in volcanic activity in Sicily and the formation of Tyrrhenian slab to the north.

References

  1. ↑ Steven M. Stanley (2004). "Mountain building". Earth system history (2nd ed.). Macmillan. p. 207. ISBN   978-0-7167-3907-4.
  2. ↑ Robert J. Twiss; Eldridge M. Moores (1992). "Plate tectonic models of orogenic core zones". Structural Geology (2nd ed.). Macmillan. p.  493. ISBN   978-0-7167-2252-6.
  3. ↑ Ollier, Cliff; Pain, Colin (2000). The Origin of Mountains . Routledge. p.  1. ISBN   978-0-415-19890-5.
  4. ↑ "Geosynclinal Theory". publish.illinois.edu. University of Illinois at Urbana-Champaign. Retrieved March 8, 2018. The major mountain-building idea that was supported from the 19th century and into the 20th is the geosynclinal theory.
  5. ↑ Kurt Stüwe (2007). "§4.5 Geomorphology". Geodynamics of the lithosphere: an introduction (2nd ed.). Springer. p. 178. ISBN   978-3-540-71236-7.
  6. ↑ Andrew Goudie (2004). Encyclopedia of geomorphology; Volume 2. Routledge. p. 701. ISBN   978-0-415-32738-1.
  7. ↑ NASA - Activity at Kliuchevskoi
  8. ↑ Victor Schmidt; William Harbert (2003). Planet Earth and the New Geoscience (4th ed.). Kendall Hunt. pp. 46–47. ISBN   978-0-7872-9355-0.
  9. ↑ Stephen D Butz (2004). "Chapter 8: Plate tectonics". Science of Earth Systems. Thompson/Delmar Learning. p.  136. ISBN   978-0-7668-3391-3.
  10. ↑ John Gerrard (1990). "Types of volcano". Mountain environments: an examination of the physical geography of mountains. MIT Press. p.  194. ISBN   978-0-262-07128-4.
  11. ↑ Robert Wayne Decker; Barbara Decker (2005). "Chapter 8: Hot spots". Volcanoes (4th ed.). Macmillan. p. 113 ff. ISBN   978-0-7167-8929-1.
  12. ↑ Arthur Holmes; Donald Duff (2004). Holmes Principles of Physical Geology (4th ed.). Taylor & Francis. p. 209. ISBN   978-0-7487-4381-0.
  13. ↑ Transactions of the American Society of Civil Engineers, Volume 39. American Society of Civil Engineers. 1898. p. 62.
  14. ↑ James Shipman; Jerry D. Wilson; Aaron Todd (2007). "Minerals, rocks and volcanoes". An Introduction to Physical Science (12th ed.). Cengage Learning. p. 650. ISBN   978-0-618-93596-3.
  15. ↑ Michael P Searle (2007). "Diagnostic features and processes in the construction and evolution of Oman-, Zagros-, Himalayan-, Karakoram-, and Tibetan type orogenic belts". In Robert D Hatcher Jr.; MP Carlson; JH McBride & JR Martinez Catalán (eds.). 4-D framework of continental crust. Geological Society of America. p. 41 ff. ISBN   978-0-8137-1200-0.
  16. ↑ Chris C. Park (2001). "Figure 6.11". The environment: principles and applications (2nd ed.). Routledge. p. 160. ISBN   9780415217705.
  17. ↑ Scott Ryan (2006). "Figure 13-1". CliffsQuickReview Earth Science. Wiley. ISBN   978-0-471-78937-6.
  18. ↑ John Gerrard (1990-04-12). Reference cited. p. 9. ISBN   978-0-262-07128-4.
  19. ↑ Lee, C.-T.; Yin, Q; Rudnick, RL; Chesley, JT; Jacobsen, SB (2000). "Osmium Isotopic Evidence for Mesozoic Removal of Lithospheric Mantle Beneath the Sierra Nevada, California" (PDF). Science. 289 (5486): 1912–6. Bibcode:2000Sci...289.1912L. doi:10.1126/science.289.5486.1912. PMID   10988067. Archived from the original (PDF) on 2011-06-15.
  20. ↑ Мичев (Michev), Николай (Nikolay); Михайлов (Mihaylov), Цветко (Tsvetko); Вапцаров (Vaptsarov), Иван (Ivan); Кираджиев (Kiradzhiev), Светлин (Svetlin) (1980). Географски речник на България[Geographic Dictionary of Bulgaria] (in Bulgarian). Sofia: Наука и култура (Nauka i kultura). p. 368.
  21. ↑ Димитрова (Dimitrova), Людмила (Lyudmila) (2004). Национален парк "Пирин". План за управление[Pirin National Park. Management Plan] (in Bulgarian). и колектив. Sofia: Ministry of Environment and Water, Bulgarian Foundation "Biodiversity". p. 53.
  22. ↑ Дончев (Donchev), Дончо (Doncho); Каракашев (Karakashev), Христо (Hristo) (2004). Теми по физическа и социално-икономическа география на България[Topics on Physical and Social-Economic Geography of Bulgaria] (in Bulgarian). Sofia: Ciela. pp. 128–129. ISBN   954-649-717-7.
  23. ↑ Bonow, Johan M. (2009). "atlantens kustberg och högslätter – gamla eller unga?" (PDF). www.geografitorget.se (in Swedish). Geografilärarnas Riksförening.
  24. ↑ Green, Paul F.; Lidmar-Bergström, Karna; Japsen, Peter; Bonow, Johan M.; Chalmers, James A. (2013). "Stratigraphic landscape analysis, thermochronology and the episodic development of elevated, passive continental margins". Geological Survey of Denmark and Greenland Bulletin . 30: 18. doi: 10.34194/geusb.v30.4673 .
  25. ↑ Japsen, Peter; Chalmers, James A.; Green, Paul F.; Bonow, Johan M. (2012). "Elevated, passive continental margins: Not rift shoulders, but expressions of episodic, post-rift burial and exhumation". Global and Planetary Change . 90–91: 73–86. Bibcode:2012GPC....90...73J. doi:10.1016/j.gloplacha.2011.05.004.
  26. ↑ Løseth and Hendriksen 2005
  27. ↑ Y Niu & MJ O'Hara (2004). "Chapter 7: Mantle plumes are NOT from ancient oceanic crust". In Roger Hékinian; Peter Stoffers & Jean-Louis Cheminée (eds.). Oceanic hotspots: intraplate submarine magmatism and tectonism. Springer. p. 239 ff. ISBN   978-3-540-40859-8.
  28. ↑ AB Watts (2001). "§7.2 Extensional tectonics and rifting". Isostasy and flexure of the lithosphere. Cambridge University Press. p. 295. ISBN   978-0-521-00600-2.
  29. ↑ GD Karner & NW Driscoll (1999). "Style, timing and distribution of tectonic deformation across the Exmouth Plateau, northwest Australia, determined from stratal architecture and quantitative basin modelling". In Conall Mac Niocaill & Paul Desmond Ryan (eds.). Continental tectonics. Geological society. p. 280. ISBN   978-1-86239-051-5.
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